However many teraflops may be claimed by the graphics processing, it’s quality control flops that end up creating the buzz about Apple’s most desirable standalone machine, the iMac 27-inch Quad Core 28GHz i7.

The most impressive aspect of the iMac is the LG-sourced LED illuminated display, which packs in 109 pixels per inch to create a 2560 x 1440 widescreen of 23.5 x 13 inch. This makes it possible for photographers to work on an actual 12 x 16 inch print area with space for palettes and menu bars, and for editors to view double-page A4 spreads at life size.

The issues with this huge screen have included cracked glass on delivery – it is covered with a slick anti-reflection coated glass you can polish without risk as the fragile LED screen and its polarising filter are sandwiched under its protection. Stuck pixels are not so common (a screen of this size could have more than 20 before it became unacceptable) but colour and brightness issues are leading to most returns and replacements. There’s even a website with test utilities (www.imac.squeaked.com) to help new owners see whether their iMac display is brighter and bluer in the top left corner, dull and yellowish the bottom right, and patchy all over. Reportedly, Apple has been unable to keep up with demand for replacements so far.

Our two iMac 27-inchers – manufactured in week 51, December 2009 – both have this issue. So far they don’t have other issues such as scratching CDs and DVDs (drive-slot alignment with casing), flickering display, overheating or errant processing threads piling up into a CPU logjam. I regularly run more than a dozen programs simultaneously, and the Quad Core i7 is at least three times faster than my outgoing 24 inch 2.16GHz iMac. The older machine would only ‘see’ 3GB of the maximum 4GB I had installed. The 64-bit capable architecture can see as much Ram as you can afford to fit in its four easily accessed slots. It’s expensive to order the iMac with Apple upgrades, and not efficient unless you state you want 8GB but two slots left vacant – otherwise you could get an 8GB machine with no room for expansion.

I felt 8GB would be enough for my intended workload, and therefore bought a machine with 4GB populated in two slots, and added the same again from Crucial (Lexar) Memory for £69+VAT. It’s a perfect match as the machine’s native memory is identical in origin and type. The difference in cost between 1TB and 2TB internal fitted drives would cover double the 1TB gain if spent on external drives, so 1TB was our choice.

Running CS4 Design Premium (Photoshop/Bridge/Indesign/Acrobat Pro), Expression Media Pro 2, Filemaker Pro 9, Firefox, Mail, Cyberduck, Neo Office and a few minor utilities gives the new machine no problems. Launching and quitting takes a fraction of the time, though the Adobe suite still has problems closing down cleanly. Firefox is the worst offender for hogging memory, and I would advise anyone who wants an efficient imaging workstation to shift their web browser and email to a different machine.

It’s important to remember that this ultra-sharp, very fine-pitch large screen shows 100 percent image views 40 percent smaller to the eye than traditional 72dpi screens once used to. Everything including text, menus, cursors and tools becomes physically smaller in scale yet on a far larger screen. If you want to judge picture sharpness, try reverting to an old 20-inch 1024 x 768 CRT.

In the past, it made little sense to work at 200 percent view in Photoshop – you got blurry big pixels and saw little of the image. On the iMac 27 inch it’s a key to maintaining quality; either that or peer closely at the huge screen, and that’s not a very comfortable option.

The laptop-scale minimal wireless keyboard and new touch-sensitive Magic Mouse work well, more so the mouse than the keyboard, which loses a few important keys such as ‘Enter’, replacing them with combinations (Fn+Return in this case). Scrolling in two directions by fingertip movement over the mouse top surface is either aided or hindered by switching on a ‘momentum’ option, depending on the program in use. You may prefer to use an older wired full keyboard, a graphics pad, or even an earlier mouse. I like the extra desk space and wire-free environment, and the way my desk machine now closely matches my Macbook egonomically.

As for the screen issue, I’ll be making an Applecare call, but there’s more than enough perfect neutral calibrated screen area in the middle – where I tend to place detail I’m working on. Even a 1080p video window sits well out of the way of that bright top left and murky bottom right zone. But at more than £1600+Vat it should be perfect even when I open four 720p videos, tile them in the screen and play them all at once – which, without a jitter, this machine proved perfectly capable of doing all from the same 1TB Firewire 800 external drive.

That’s how big the screen is – four times HD 720p – and that’s how much power it offers. Expect to see these machines in studios and at trade shows everywhere, QC problems or not.